AU604162B2

AU604162B2 - Fluorescent display apparatus

Info

Publication number: AU604162B2
Application number: AU23617/88A
Authority: AU
Inventors: Zenichiro Hara; Shuuji Iwata; Masaaki Kobayashi; Kazunori Tatsuda; Nobuo Terazaki
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 1987-10-12
Filing date: 1988-10-11
Publication date: 1990-12-06
Anticipated expiration: 2008-10-11
Also published as: JPH0587932B2; DE3880254T2; EP0311951A2; US4893056A; DE3880254D1; HK34996A; EP0311951B1; JPH01100854A; AU2361788A; EP0311951A3; CA1296047C

Description

AUSTRALIA

PATENTS ACT 1952 COMPLETE SPECIFICATION Form

(ORIGINAL)

FOR OFFICE USE 604162 Short Title: Int. Cl: Application Number: Lodged: Complete Specification-Lodged: Accepted: Lapsed: Published: S.Priority: S Related Art: amendments made under Section 49 and is correct for printing.

0 0 0 te& a TO BE COMPLETED BY APPLICANT Name of Applicant:

MITSUBISHI

KAISHA

DENKI KABUSHIKI Address of Applicant: o 4 a 'Actual Inventor: *--,Address for Service:

I

2-3, MARUNOUCHI 2 CHOME

CHIYODA-KU

TOKYO 100

JAPAN

GRIFFITH HACK CO., 601 St. Kilda Road, Melbourne, Victoria 3004, Australia.

Complete Specification for the invention entitled: FLUORESCENT DISPLAY APPARATUS The following statement is a full description of this invention including the best method of performing it known to me:- FLUORESCENT DISPLAY APPARATUS BACKGROUND OF THE INVENTION Field of the Invention The present invention relates to a fluorescent display apparatus constituting a large-screen display for use in a stadium or the like.

Description of the Prior Art Large-screen displays are in use for displaying tt C progress and result of sports events in such places as an outdoor stadium. A fluorescent display apparatus utilized in such a large-screen display is constructed of a large number of monochromatic illuminating tubes arranged in a matrix. FIG. 1 is a schematic diagram f tshowing an internal arrangement of a prior art monochromatic illuminating tube.

The interior of the glass tube 1 is in a vacuum with air inside the tube evacuated through an exhaust hole 2. As a heater 3 heats up a cathode 4 surrounding the heater 3, thermoelectrons are emitted from the cathode 4. The thermoelectrons emitted from the cathode 4 is controlled in their flow by three types of grids J 6, 7 and allowed to bombard a fluorescent display portion 8 coated with fluorescent material. The fluorescent display portion 8 is applied with a high voltage and the part of the fluorescent display portion 8 bombarded by the thermoelectrons emits light. The grid 5 controls the quantity of the thermoelectrons emitted from the cathode 4, the grid 6 controls the diameter of the beam of the emitted thermoelectrons, and the grid 7 accelerates the emitted thermoelectrons.

While potential for the grids 6, 7 is fixed, potential for the grid 5 is controlled, and thereby the quantity of the emitted thermoelectrons is controlled and the brightness of the fluorescent display portion 8 is regulated.

So* 10 FIGS. 2 and 3 show a fluorescent display apparatus integrating a number of such monochromatic illuminating 0 T r tubes therewith. On the apparatus, there are disposed *J the fluorescent display portions 8 of three primary colors, red green and blue colors, i 15 suitably spaced apart in vertical and horizontal t directions so as to be regularly distributed. Thus, j with the potential of the grid 5 of each of the monochromatic illuminating tubes controlled, each of the fluorescent display portions 8 are controlled in their 20 brightness and thereby a display is given with a desired color tone.

As a means to improve the resolution of such an apparatus provided with a number of monochromatic illuminating tubes, there is one using an illuminating tube being provided with a plurality of fluorescent display portions. However, since such an apparatus is of the structure that the cathode and grids must be 2

J

provided for each of the fluorescent display portions, there are problems with it that the number of the component parts of the fluorescent display apparatus becomes larger, the internal structure becomes complex, and the power consumption becomes larger.

SUMMARY OF THE INVENTION A primary object of the present invention is the provision of a fluorescent display apparatus having a ,e simpler internal structure and consuming smaller power.

t 10 Therefore, according to one aspect of the invention, there is provided fluorescent display apparatus 0004 :00o" comprising a vacuum chamber containing cathodes for f emitting thermoelectrons, control electrodes for controlling the flow of the emitted thermoelectrons, and a display portion formed of a plurality of fluorescent display portions coated with fluorescent material and emitting light upon being bombarded by thermoelectrons, and wherein said display portion is. formed..of said 20 fluorescent display portions arranged in a matrix of 2m rows by n columns n are natural numbers), said cathodes are made up of cathodes in a linear form oriented in the direction of the row or column and disposed to oppose said display portion arranged in an array of m rows by n columns so that one each thereof corresponds to two of said fluorescent display portions, and 3 I said control electrodes are made up of a first control electrode in a planar form for controlling the passage of thermoelectrons.from the cathode to the display portion being disposed between said display portion and said cathodes and having openings made therein corresponding to said fluorescent display portions of said display portion, second control electrodes each one of which is disposed behind and in line with a one of said cathodes with respect to said display portion for I i, 10 controlling the emission of thermoelectrons from C C the cathode and arranged in an array of m rows by n o° •1 columns so that each thereof is disposed corresponding to each said cathode, and third control electrodes arranged in an array of 2m rows by n columns and being disposed on two sides of said second control .electrodes so that each too, thereof is oriented in the direction of the column of said 4 1 second control electrodes, the third control electrodes controlling the advancing direction of the thermoelectrons emitted from a respective cathode.

t c 20 According to a further aspect of the invention, rr, there is provided fluorescent display apparatus comprising a vacuum chamber containing cathodes for emitting thermoelectrons, control electrodes for controlling the flow of the emitted thermoelectrons, and a display portion W 25 formed of a plurality of fluorescent display portions coated with fluorescent material and emitting light upon 3A

C'

IC

.I

-1 being bombarded by the thermoelectrons, and wherein said display portion is formed of said fluorescent display portions arranged in a matrix of 2m rows by 2n columns n are natural numbers), said cathodes are made up of cathodes in a linear form oriented in the direction of the row and disposed to oppose said display portion arranged in an array of m rows by n columns so that one each thereof corresponds to four of said fluorescent display portions, and said control electrodes are made up of a first control electrode in a planar form for controlling the emission of thermoelectrons from the cathode dto the display portion being disposed between said display portion and said cathodes and having 2m x 2n openings r.ade therein corresponding to said fluorescet display portions of said display portion, second control electrodes each one of which is disposed behind and in line with a one of said cathodes with -respect-to said display portion for controlling the emission of thermoelectrons from the cathode and arranged in an array of m rows by 2n columns so that two each thereof is disposed, corresponding to each said cathode along the length of the cathode, and third control electrodes disposed, corresponding to each said cathode, on two sides of said two second control electrodes so that each thereof is oriented in the direction of the column of said second control electrodes, the third control electrodes controlling the advancing direction of the thermoelectrons emitted from a respective 30' cathode. -I 6" aS .(2 #1.1 I

B

3B openings in the first control1~ e Te. Thus, the fluorescent disp@i-y= pTrt-ions emit light individually BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing internal structure of a prior art monochromatic illuminating tube; FIG. 2 is a top view of a prior art fluorescent 10 display apparatus; FIG. 3 is a side view in section of the same; t c C 4:ce FIG. 4 is an exploded view in perspective showing f, component parts of an embodiment of the present invention; cc FIG. 5 is a plan view showing electrode structure; 15 FIG. 6 is a timing chart schematically showing timing of signals; FIG. 7 is a schematic plan view showing a display portion; FIGS. 8 and 9 are schematic diagrams showing state fc tcr of potential in the vicinity of cathodes; S FIG. 10 is a plan view showing electrode structure of another embodiment of the present invention; FIG. 11 is an exploded view in perspective showing component parts of still other embodiment of the present invention; and FIG. 12 is a plan view showing electrode structure of the embodiment of FIG. 11.

4 I: I tr It a t C C C C V f Ve e C C CCC t C t C~l GStC I C DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Below will be described a fluorescent display apparatus having display portions arranged in a matrix of two rows by two columns as an embodiment according to the present invention with reference to the accompanying drawings.

FIG. 4 is an exploded view in perspective showing component parts of an embodiment of a fluorescent display apparatus according to the present invention. Referring to the figure, la denotes a display portion in a planar form having 16 fluorescent display portions 8, lb denotes a frame member constituting +-he side walls of the fluorescent display apparatus, 14 denotes a planar electrode as a first control electrode having 16 15 openings 15 made therein, and lc denotes a substrate with cathodes 4, second and third control electrodes 12, wiring electrodes 11, 13 therefor and the like formed thereon. The fluorescent display apparatus is assembled by having a planar electrode 14 disposed in 20 the space surrounded by the frame member lb, attaching the display portion la to one side of the frame member Ib, and attaching the substrate ic to the other side of the frame member lb.

The display portion la has 16 fluorescent display portions 8 arranged in a matrix (four rows by four columns) and coated with fluorescent material. Each fluorescent display portion 8 is applied with a high 5 i. voltage and emits light when bombarded by thermoelectrons. The planar electrode 14 is provided with 16 openings 15 made therein, arranged in a matrix (four rows by four columns), at the positions corresponding to their respective fluorescent display portions 8.

FIG. 5 is a plan view showing the electrode arrangement on the substrate ic, in which the horizontal direction corresponds to the direction of the row and 1 0 the vertical direction corresponds to the direction of ot the column. In the center of the substrate lc, there is C ge formed an exhaust hole 2 as the passage for evacuating air from the interior of the fluorescent display apparatus. There are provided eight directly heated, linear cathodes 4 disposed slightly separated from the surface of the substrate Ic. As each cathode 4 is heated by electric current passed therethrough, thermoelectrons are emitted from the cathode 4. At the portions on the surface of the substrate ic opposing each of the cathodes 4, there are formed eight data electrodes 10 as second control electrodes for controlling the emission of the thermoelectrons from the cathodes 4 in an array of two rows by four columns. Each data electrode controls the emission of the thermoelectrons from each of the corresponding cathodes 4 by being applied with a positive or negative potential relative to the potential of the cathode 4. On the surface of the substrate Ic 6 =u~~~ls*pi 7 C C

CC

C

c t and at both sides of each of the data electrodes 10 in the direction of the column, there are formed 16 scanning electrodes 12 as third control electrodes for controlling the advancing direction of the thermoelectrons emitted from the cathode 4 arranged in a matrix of four rows by four columns. The data electrode 10 has smaller surface area than the scanning electrode 12. Of the eight data electrodes 10, two each arranged in the direction of the column are connected to each of four wiring electrodes 11 arranged in the direction of the column. Of the 16 scanning electrodes 12, four each arranged in the direction of the row are connected to each of four wiring electrodes 13 crossing the wiring electrodes 11 at right angles, or arranged 15 in the direction of the row. The wiring electrodes 11 and the wiring electrodes 13 are arranged so as not to contact each other through an insulating layer. And, these data electrodes 10, scanning electrodes 12, wiring electrodes 11, and wiring electrodes 13 are printed on the surface of the substrate ic.

Below will be described operation of the apparatus.

Referring to FIG. 5, SI, S2, and S 4 denote scanning signals to be applied, respectively, to four scanning electrodes 12 each in the direction of the row, while D

I

D

2

D

3 and D 4 denote data signals to be applied, respectively, to four data electrodes 10 each in the direction of the column. FIG. 6 is for showing timing 7 of application of these signals S S and D D And, FIG. 7 is for showing the arrangement of the fluorescent display portions 8 formed in a matrix on the display portion la, wherein the fluorescent display portions 8 are controlled in their emission of light by the control of the signals S 1 S4 and D 1

D

4 The operation for controlling the emission of light will be described below.

ON (positive) or OFF (negative) state of each of S° 10 the data electrodes 10 and ON (positive) or OFF P (negative) state of each of the scanning electrodes 12 are controlled by the timing of application of the data signals and the scanning signals. With regard to the ON or OFF state of the scanning electrode 12 and the ON or Ca 15 OFF state of the data electrode 10, there are four C cases: the case where both the scanning electrode 12 and the data electrode 10 are in the ON state, where the scanning electrode 12 is in the ON state and the data electrode 10 is in the OFF state, where the scanning f: 20 electrode 12 is in the OFF state and the data electrode is in the ON state, and where both the scanning electrode 12 and the data electrode 10 are in the OFF state. The condition of emission of light by the fluorescent display portion 8 in each case will be described below. FIGS. 8 and 9 are schematic diagrams showing states of potential in these four cases.

8 -I ~t C 1 r 4 t e

C

cc ~t

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CCC?

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4, 'ii 34 6 4 t Q Where bcith the scanning electrode 12 and the data electrode 10 are in the ON state: The electric field in the vicinity of the heated cathode 4 becomes positive on account of the electric field of the data electrode 10 and the scanning electrode 12 and hence thermoelectrons are emitted. The emitted thermoelectrons are deflected by the electric field ot the scanning electrode 12 and accelerated by the planar electrode 14 to advance to the corresponding fluorescent 10 display portion 8 and bombard the fluorescent display portion 8. Then, the thermoelectrons coming into contact with the fluorescent material causes the fluorescent display portion 8 to emit light (FIG. 8 Q 0 Where the scanning electrode 12 is in the ON state and the data electrode 10 is in the OFF state: Since the data electrode 10 is formed closer to the cathode 4, the electric field of t'Ie data electrode affects the cathode 4 more strongly. Hence, in this case, the electric field in the vicinity of the cathode 20 4 becomes negative so that the emission of the thermoelectrons from the cathode 4 is restrained and the fluorescent display portion 8 does not emit light (FIG.

0 Where the scanning electrode 12 is in the OFF state and the data electrode 10 is in the ON state: Although the data electrode 10 is positive, both the scanning electrodes 12 formed on both sides of the 9data electrode 10 are negative, and moreover, the scanning electrode 12 is larger in surface area than the data electrode 10, and hence the electric field in the vicinity of the cathode 4 becomes negative so that the emission of the thermoelectrons from the cathode 4 is restrained and the fluorescent display portion 8 does not emit light (FIG. 8 Where both the scanning electrode 12 and the data electrode 10 are in the OFF state: S 10 The electric field in the vicinity of the cathode 4 c becomes negative so that the emission of the thermori electrons from the cathode 4 is restrained and the fluorescent display portion 8 does not emit light (FIG.

15 In the described manner, the emission of light by each of the fluorescent display portions 8 is controlled at will by combination of the potential of the data electrode 10 and the scanning electrode 12. Since, here, the potential of the data electrode 10 and the scanning 20 electrode 12 is controlled by the data signals D 1

D

4 and the scanning signals S 1 S4, it is enabled to have each of the fluorescent display portions 8 emitting light or not at will by the control of these signals.

The relationship in concrete terms between the control of signals and the control of light emission in each of the fluorescent display portions 8 will now be described according to Fig. 7. First, when the scanning 10 signal S 1 is ON, fluorescent display portions P 11

P

14 'I are selected, and according to ON/OFF states of the data signals D 1 D, the corresponding fluorescent display portions 8 are chosen whether or not to emit light.

Then, upon turning ON of the signal S h loecn display portions P 1

-P

4 are selected and, according to ON/OFF states of the data signals D 1 Dsilay 10 UpntunniOmfihligasarl4ysmial t h toeabove,th corresponding fluorescent display rin 'Cer according to ON/OFF states of the data signals D D D are chosen whether or not to emit light. Thus, by the application of the timing signals as shown in FIG. 6, T0C t CC CcrC 15 the conditions of the fluorescent display portions 8 whether or not to emit light can be controlled will.

By the construction and the control of the fluorescent display apparatu~s described above, the number of the cathodes can decrease by half and the pc~wer consumption can alsc be made smaller as compared with the prior art fluorescent display apparatus.

FIG. 10 is another embodiment of the present invention wherein the cathodes are arranged in the column direction. Thus arrangement, as the cathode length is longer than that in Fig. 4 wherein the cathodes are arranged in the row direction, the emission efficiency of the thermoelectrons is better and the power consumption can furthermore decrease.

11 FIGS. 11 and 12 are still other embodiment of the fluorescent display apparatus of the present invention having display portions which are arranged in four rows by four columns.

FIG. 11 is a plan view showing the electrode arrangement on the substrate Ic, in which the horizontal direction corresponds to the direction of the row and the vertical direction corresponds to the direction of the column. In the center of the substrate lc, there is formed an exhaust hole 2 as the passage for evacuating air from the interior of the fluorescent display r.

c, apparatus. There are provided four directly heated, linear cathodes 4 disposed slightly separated from the surface of the substrate lc. As each cathode 4 is 15 heated by electric current passed therethrough, ,e thermoelectrons are emitted from the cathode 4. At the portions on the surface of the substrate lc opposing each of the cathodes 4, there are formed eight data electrodco 10 as second control electrodes for controlling the emission of the thermoelectrons from the cathodes 4 in an array of two rows by four columns.

Each data electrode 10 controls the emission of the Sthermoelectrons from each of the corresponding cathodes 4 by being applied with a positive or negative potential relative to the potential of the cathode 4. On the surface of the substrate lc and at both sides of each of the data electrodes 10 in the direction of the column, 12

I

there are formed eight scanning electrodes 12 as third control electrodes for controlling the advancing direction of the thermoelectrons emitted from the cathode 4 arranged in a matrix of four rows by two columns. The data electrode 10 has smaller surface area than the scanning electrode 12. Of the eight data electrodes 10, two each arranged in the direction of the column are connected to each of four wiring electrodes 11 arranged in the direction of the column. Of the 1 i0 eight scanning electrodes 12, two each arranged in the direction of the row are connected to each of four c wiring electrodes 13 crossing the wiring electrodes 11 at right angles, or arranged in the direction of the

I

row. The wiring electrodes 11 and the wiring electrodes S 15 13 are arranged so as not to contact each other through

D

Ec V an insulating layer. And, these data electrodes U scanning electrodes 12, wiring electrodes 11, and wiring c electrodes 13 are printed on the surface of the substrate ic.

7< 20 The operation of the fluorescent display apparatus r thus constructed is the same as that of FIG. 4. By the above construction of the fluorescent display apparatus, the number of the cathode can decrease by quarter and the power consumption can also be made smaller as compared with the prior art fluorescent display apparatus.

13 1' According to the present invention, the control electrodes are arranged in a matrix, light emitting conditions of the fluorescent display portions 8 are controlled for each row by the scanning signal, and the light emitting conditions of the fluorescent display portions 8 for each column are controlled by the data signal, and therefore, the peripheral circuits for the control electrodes can be made smaller in number as compared with the prior art fluorescent display apparatus 1 0 wherein the fluorescent display portions 8 are S individually controlled for emitting light.

0 0 °oe Further, the data electrodes, scanning electrodes, oo o and wiring electrodes for these electrodes are formed on the same surface by printing, and hence the internal S 15 structure can be made simpler.

o Although the present embodiment was described above as to its case where four rows by four columns, but c ICC these are not limitative. Even if more numbers of roww and column are used, similar arrangement as above can of course be realized.

According to the present4ine{ as described above in detail, cathodes in a linear form are used as the cathodes, and besides, a single cathode is arranged to be commonly used for two or four, or. further more fluorescent display portions, and hence the power consumption can be kept lower.

14 Further, since the number of peripheral circuits of the control electrodes is reduced on account of the arrangement that emission of light by the fluorescent display portions arranged in a matrix is controlled for each row and each column, the effect is obtained that the internal structure of the fluorescent display apparatus can be made simpler.

C

C cc tC

U

15

Claims

1. Fluorescent display apparatus comprising: a vacuum chamber containing cathodes for emitting thermoelectrons, control electrodes for controlling the flow of the emitted thermoelectrons, and a display portion formed of a plurality of fluorescent display portions coated with fluorescent material and emitting light upon being bombarded by thermoelectrons, and wherein said display portion is formed of said fluorescent display portions arranged in a matrix of 2m rows by n columns n are natural numbers), 1 said cathodes are made up of cathodes in a !If linear form oriented in the direction of the row or column and disposed to oppose said display portion arranged in an S ^rc array of m rows by n columns so that one each thereof corresponds to two of said fluorescent display portions, Sand I said control electrodes are made up of a first control electrode in a planar form for controlling the passage of thermoelectrons from the cathode to the display portion being disposed between said display portion and said cathodes and having openings made therein corresponding to said fluorescent display portions of said display portion, second control electrodes each tc., of which is disposed behind and in line with a one of said cathodes with respect to said display portion for 16 lC__l^L_ Lrre YIPrYII~YY r~ I controlling the emission of thermoelectrons from the cathode and arranged in an array of m rows by n columns so that each thereof is disposed corresponding to each said cathode, and third control electrodes arranged in an array of 2m rows by n columns and being disposed on two sides of said second control electrodes so that each thereof is oriented in the direction of the column of said .second control electrodes, the third control electrodes rr controlling the advancing direction of the thermoelectrons emitted from a respective cathode. V

2. Fluorescent display apparatus as claimed in claim 1, wherein said second and third control electrodes and wiring therefor are all formed on the same surface by printing.

3. Fluorescent display apparatus as claimed in S either one of claims 1 or 2, wherein groups of said second control electrodes for each column are connected to 2n signal lines, while groups of said third control electrodes for each *row are connected to 2m signal lines crossing the 2n signal lines at right angles.

4. Fluorescent display apparatus comprising: a vacuum chamber containing cathodes for emitting thermoelectrons, control electrodes for |i controlling the flow of the emitted thermoelectrons, and a display portion formed of a plurality of fluorescent display portions coated with fluorescent material and emitting light upon being bombarded by the 17 thermoelectrons, and wherein said display portion is formed of said fluorescent display portions arranged in a matrix of 2m rows by 2n columns n are natural numbers), said cathodes are made up of cathodes in a linear form oriented in the direction of the row and disposed to oppose said display portion arranged in an array of m rows by n columns so that one each thereof .K, corresponds to four of said fluorescent display portions, Sand °C said control electrodes are made up of a first control electrode in a planar form for controlling the emission of thermoelectrons from the cathode dto the display portion being disposed between said display Sportion and said cathodes and having 2m x 2n openings made C therein corresponding to said fluorescent display portions of said display portion, second control electrodes each I I one of which is disposed behind and in line with a one of said cathodes with respect to said display portion for controlling the emission of thermoelectrons from the cathode and arranged in an array of m rows by 2n columns i so that two each thereof is disposed, corresponding to Seach said cathode along the length of the cathode, and |third control electrodes disposed, corresponding to each Ssaid cathode, on two sides of said two second control electrodes so that each thereof is oriented in the 18 I~ _I direction of the column of said second control electrodes, the third control electrodes controlling the advancing direction of the thermoelectrons emitted from a respective cathode.

Fluorescent display apparatus as claimed in claim 4, wherein said second and third control electrodes and wiring therefor are all formed on the same surface by i printing.

6. Fluorescent display apparatus as claimed in Seither one of claims 4 or 5, wherein groups of said second id control electrodes for each column are connected to 2n signal lines, while groups of said third control electrodes for each row are connected to 2m signal lines S crossing said 2n signal lines at right angles. DATED THIS 12TH DAY OF SEPTEMBER, 1990 MITSUBISHI DENKI KABUSHIKI KAISHA By Its Patent Attorneys GRIFFITH HACK CO. Fellows Institute of Patent SAttorneys of Australia I i u 19